The fire was intentionally set, she said, and fireworks were found throughout the house at 16223 Sierra de Avila.

Authorities have not ruled out the possibility that the killer was one of the four. The colonel said she doesn't believe neighbors are in danger.

The names of the dead went untold by authorities because no one could be 100 percent sure.

But when two teens who lived in the home failed to show up for school, the mourning began.

Even before Hillsborough County sheriff's investigators could step foot inside, the loss spilled out of the texts and tweets of high school students, who would have grief counselors among them by day's end.

Ryan Kelly, head of the Carrollwood Day School, said hearts were broken there.

"The tenor of the school is sadness," he said.

Voter records identify the leased Avila home as the address of Carrollwood Day School treasurer Darrin James Campbell, 49, his wife, Kimberly Ann Campbell, 51, son, Colin, 17, and daughter, Megan, a few years younger. Both teens were enrolled at the private school.

The Sheriff's Office said the deceased include two adults and two teens. Two are male and two female. The agency stopped short of positively identifying the Campbells — leaving that to the Medical Examiner's Office — but said the family has not otherwise been accounted for.

Two adults were found in one bedroom; the teens were each found in separate bedrooms.

It could take days before the remains are positively identified.

"If you have four individuals that live at this address and we have discovered four individuals, people automatically assume these are the four individuals," said sheriff's spokeswoman Debbie Carter. "In our position, we can't say that's who it is until the medical examiner says."

The 911 calls started coming in about 5:45 a.m.

"I was walking my dogs and the house just exploded," said one frantic woman.

As Hillsborough County Fire Rescue crews battled the blaze, they found two bodies, then a third, then a fourth.

The home burned for several hours, flames fanned by high winds. Initially, authorities expressed concern about the structural integrity and said it might not be possible to get detectives inside the home until Thursday. But by mid afternoon, investigators had obtained a search warrant and entered.

Lusczynski said the fire appeared to have been fed by an unknown accelerant and noted that small commercial fireworks were found through the home.

No weapons had been recovered as of a 5:30 p.m. news conference. The Sheriff's Office did not disclose the nature of the upper body trauma — a term sometimes used to describe gunshot or knife wounds.

Deputies are working with Avila neighbors to seek surveillance video that might be helpful in the investigation.

The home is owned by former professional tennis player James Blake but had been leased to the Campbells.

Blake's agent said he was not in the house at the time.

"He is living in Connecticut now and he was not living in the house," said Blake's agent, Molly Logan, with IMG Client Services in the company's Miami office.

The 5,856-square-foot home, completed in 2005, included five bedrooms and five bathrooms, along with a screened-in pool and spa. Property records put its market value at just over $1 million.

Avila, north of Tampa, is known for extravagant homes and rigid security, but the gated community has been the scene of tragedy before. In 2012, retired physician Hector Rivera, 76, and his wife, Debra Rivera, 55, were shot in their home. Charges are still pending against Julian Ospina-Florez, a business associate of the wife.

The Campbells had lived in Blake's leased home for two years, the Sheriff's Office said.

They were once a family that played a lot of putt-putt golf and visited Walt Disney World a half-dozen times a year, according to a 2005 article in the Times.

Back then, Darrin Campbell was an executive with PODS Inc. in Clearwater, and had previously worked for Anchor Glass. More recently, he was vice president for operations at IVANS Insurance Solutions in Tampa, his LinkedIn profile shows.

"Darrin Campbell was an employee of IVANS several years ago," the company said in a statement. "Our thoughts and prayers are with him, his family and friends affected by this terrible tragedy."

In recent times, Colin was known for baseball talents, listed on the leader board for batting average and home runs on a recruiting website.

On his Facebook page, he liked the Denver Broncos, the Tampa Bay Bucs, Michigan football, baseball and IHOP. About to graduate, he posted a photo of himself April 7 in a tuxedo and silver tie with friends and the caption "Prom with my bros!"

Megan took dance classes for the past three years. Her Twitter profile has pictures of her with friends, one a selfie with another girl, one at the beach. She retweeted a celebrity pic of Beyonce and another of Josh Hutcherson as Peeta Mellark in The Hunger Games, calling him, in a hashtag, a fictional character she wanted to marry.

She tweeted happy birthday messages to friends and celebrities like rapper Riff Raff.

But others were tweeting Wednesday, and invoking the name of the family that had lived in the now-charred house on Sierra de Avila.

"Still doesn't seem real to me," wrote one person. "You'll be missed by so many Colin. Rest in peace Campbell family."

News researcher John Martin, staff writer Antonya English and Josh Rojas from Bay New 9 contributed to this report.